Daniel Reetz, the founder of the DIY Book Scanner community, has recently started making videos of prototyping and shop tips. If you are tinkering with a book scanner (or any other project) in your home shop, these tips will come in handy. https://www.youtube.com/channel/UCn0gq8 ... g_8K1nfInQ

Halogen lighting - heat

All about lighting. LED, CFL, Halogen, Other? Questions and info about lighting go here.
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Misty
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Halogen lighting - heat

Post by Misty » 06 Nov 2009, 17:17

I've been looking at what lighting system to use for my cradle. While the LED setup Daniel has in his new thread looks great, I don't have (or have access to) the electrical expertise to wire something similar up myself. I'm looking at halogen instead, but I'm concerned about the heat output. My cradle will have a black canvas light shield around it, and I want to be sure there isn't a chance of any fire danger from having that so close to a halogen light. Has anyone done anything to minimize heat in their designs?
The opinions expressed in this post are my own and do not necessarily represent those of the Canadian Museum for Human Rights.

Snapabook
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Re: Halogen lighting - heat

Post by Snapabook » 07 Nov 2009, 10:20

Halogen lights with a proper heat shielding can minimize a fire when something that can burn come onto contact with them. For example, this halogen light from tooltrolley.co.uk (on the left) doesn't have the front grill guard. Fabrics falling in front of it can burn. On the other hand the one from hygienesuppliesdirect.com (on the right) has a metal grill to protect it from combustibles from coming too close. But if you can keep things away from the front of the lights then you can use either one. The black part of the lights aren't hot enough to burn things, but don't just throw a cloth on top of the light as it may burn.
lights.jpg
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To avoid a fire problem you can try draping behind the cameras, but leave the areas above the light open. The high output of the halogen will also help drown out any glare problems. Glare problems usually occur under low light.

If you really want to drape right above the light, because your boss wants absolutely no glare, leave a funnel shape air vent (a sizable hole on the fabric right above the lights, much like an Indian Tipi, to vent out that heat.) If you're using an expose halogen bulb (on a properly rated socket) then I would guess you'll need a 3 to 5 inches space between the light and the fabric with a funnel shape Tipi hole above it.

Often, a high output light like this makes people who scan very old book scorn. The light may age the books. So what people often do is set the camera to manual focus/exposure and switch on the lights only at the instance the camera is taking the photo.


* The images are copyrighted... so to meet their copyright requirements, we have to comment on them.
Last edited by Anonymous on 10 Nov 2009, 09:35, edited 1 time in total.

jrichards
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Re: Halogen lighting - heat

Post by jrichards » 07 Nov 2009, 12:57

If you are going to use a halogen light you could follow this simple tutorial and switch out the halogen light for a CFL bulb. Here is the link for the tutorial: http://www.flickr.com/photos/mhuk/3311771227/

I did this with my light and it provides very good and even lighting. It was also very simple to do.

spamsickle
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Re: Halogen lighting - heat

Post by spamsickle » 07 Nov 2009, 20:14

I'd be reluctant to switch halogens for CFLs in this application because of the reputation CFLs have for diminishing light levels as they age. Halogens are known for nearly constant output over their lifetimes, which allows me to use the same manual exposure settings every time rather than recalibrating them periodically as light levels change. If you're getting good results, though, all these theoretical considerations don't really matter.

Snapabook
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Re: Halogen lighting - heat

Post by Snapabook » 08 Nov 2009, 10:30

If I were to use CFL (which I won't) I would get me a nice quality Cold Cathode CFL for capturing fine details and improving sharpness, which the LED can do the same. Cold Cathode lamps found in flatbed scanners, which calibrate at every startup, appears to maintain its brightness throughout its lifetime even though the scanner itself is outdated. However, if the camera optics are poor to begin with, Cold Cathode CFL might not make a difference.

I avoid CFL lightnings because of a matter of principle. The reason I'm against CFL is the mercury level in them. Watch Ted Poe talks about CFL bulbs on Youtube. http://www.youtube.com/watch?v=Tv59PJ30WeM . As a custodian of mother Earth, it's our hope and duty to rid mercury once and for all from contaminating our environment. And to keep all of us bright and creative as we maintain a mercury-free body. The choices of LED lighting varieties in the market are almost virtually endless. They are much safer to your dark fabrics, to your books and to your body. The choice is yours.

matt1985
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Re: Halogen lighting - heat

Post by matt1985 » 08 Nov 2009, 13:15

I avoid CFL lightnings.

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